96 T-bird emissions (I guess?) prob

That light! That light! I bet you know which one I'm talking about. Yep, that blasted check engine light!
It first came on around 32k miles (the car now has 46k -- no, it isn't
driven much). The light is accompanied by clatter, which worsens as the engine reaches operating temp, and is extremely bad during load. Even a modest grade overpass makes it sound like the valves are gonna blow thru the hood. There is, however, no discernible clatter at idle. From what I've read, it seems as though this may be "detonation", as it sounds exactly like shuffling a deck of metal playing cards.
Took it to a ford "specialist" mechanic with a good reputation, who promptly plugged in his enormously expensive portable code reader, demonstrated it to me in the car, assuring me "this and this" is the prob and began replacing parts. It turned out to be an easter egg hunt, as the light would come back on around 24 hours after each part they replaced. So far, the DPFE sensor, EGR valve (twice), O2 sensors and fuel pump have been replaced -- each part required a separate visit to (and diagnosis by) the garage. The light remains lit. The specialists finally threw their hands in the air and provided me with what ended up to be the least expensive "solution" from them yet: "put black electrical tape over the light on the dash". Yep, that's the best they could do for me after all those costly repairs.
The vehicle continues to pass state inspection -- just prior to inspection, I reset the computer by disconnecting and reconnecting the battery. No light + good emissions = passing grade. Fuel economy doesn't seem affected as yet, either.
This model had a recall for leaky/cracked intake manifolds. Took it to the dealer as soon as I received the recall notice and it checked out ok.
So, what's your best guess as to the probable cause? If this is, in fact, detonation, what part(s) should I look at which might be erroneously telling the computer to lean up the fuel mixture? Since it gets worse after warmup, should I be looking at some sort of bimetal or air flow/mix sensor? I have no service lit. on this car, and after all the bad experiences at a pro shop, I'm none too confident in OBD II code readers as diagnostic tools, either.
TIA, Ray
P.S. Remove SPAMRID from address..
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"Ray L. Volts" wrote:

Your experts should have nailed this on just on experience. I would be very surprised if it's not the MAF sensor. The cards description is a good one. It's a simple matter to fix it, just requires careful cleaning. I'll remove SPAMRID and send you some pictures and descriptions.

The light on my 97 has been on forever it seems. I'm at 119 K, it runs like a dream and smogged with no problem. Others here may have some ideas on that.
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If this is a 4.6L engine the EGR passage under the throttle body may be clogged with carbon. The elbow of the throttle body can be removed and the passage can be cleaned with very little trouble, takes about an hour.
A quick way to test for a clogged passage is to apply vacuum the EGR valve with the engine at idle. The engine should stall or run very rough when vacuum is applied at idle. If there is no noticeable change in the engine when the vacuum is applied then the passage is clogged.
To apply vacuum to the EGR valve, trace the vacuum hose from the valve to the EGR control solenoid. This will be a black solenoid located near the EGR valve. Remove the round vent cover on top of the solenoid and with the engine at idle place a finger over the vent nipple on top of the solenoid. This will apply vacuum to the EGR valve and cause it to open. This is of course assuming that all vacuum lines and the EGR valve are in working order.
Good luck
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If this is a 4.6L engine the EGR passage under the throttle body may be clogged with carbon. The elbow of the throttle body can be removed and the passage can be cleaned with very little trouble, takes about an hour.
A quick way to test for a clogged passage is to apply vacuum the EGR valve with the engine at idle. The engine should stall or run very rough when vacuum is applied at idle. If there is no noticeable change in the engine when the vacuum is applied then the passage is clogged.
To apply vacuum to the EGR valve, trace the vacuum hose from the valve to the EGR control solenoid. This will be a black solenoid located near the EGR valve. Remove the round vent cover on top of the solenoid and with the engine at idle place a finger over the vent nipple on top of the solenoid. This will apply vacuum to the EGR valve and cause it to open. This is of course assuming that all vacuum lines and the EGR valve are in working order.
Good luck
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Good call!! The elements were caked with black soot-like deposits on the inlet side. Those filaments sure are tiny and the windings are so closely spaced, it's no wonder buildup occurs. I had to use an 8x magnifier just to make sure they were perfectly clean.
The spray couldn't dislodge all of the gunk, so I finished it off with a cotton swab dipped in 91% alcohol. To anyone else who may have to clean one of these, be very careful, as they are obviously highly fragile elements. If you use a swab, you'll need a steady hand. Let the loaded swab's weight do the work, gently raking it over the windings -- do NOT apply pressure or scrub. I didn't price this part out, but it's likely a dealer-only part and likely co$tly to replace.
As a consumer electronics tech, I have a bunch of cleaners and bits in inventory, but I didn't have the T20 security bit. Couldn't find it on Rat Shack's site, so I made a run to one of my electronics parts houses and picked up one of those 33-piece sets.
Total cost of repair: about 8 bucks!
This was an extremely simple and inexpensive fix. If the CEL lamp stays off, that's proof enough this one part has been the source all along and I'll be extremely annoyed with a certain Ford shop in town.
Thanks so much for the info (I got your email, too)! You were right. The result is nothing less than amazing! Performance is like-new again and I now have peace of mind. I am one happy camper! =D
P.S. Since I already had a hand-held vac pump in my arsenal, I pulled down the EGR valve just to be sure. The engine stumbled as expected. But thanks go out to mdeee and Swanny for their effort anyhow. ;)

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Check out code P0401 on this site, it sounds like that might be the problem. It's common with 4.6L Fords. http://www.obd-codes.com
Getting the actual code will help tremendously.

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Swanny wrote:

I purchased a OBD-II tool for my '96 T-Bird, and it has paid for itself many times over. I always pull the code, write it down, clear it and make sure it comes back again before taking it in. Sometimes the code won't come back.
As for the tapping- I have that in my bird with 171k on it- I had them clean the MAF, and the problem got better, but didn't go away entirely. My current solution is to just turn up the radio. Having this car being my only transportation, I'm not too quick to start taking stuff apart on it.
Anyone know what a new MAF sensor goes for?
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m262007 wrote:

Not much to take apart. Two screws holding it in place are right next to the air cleaner. Just delicate and must be handled carefully.
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It's a delicate component, but easily accessible. In researching an unrelated issue with my bird, I ran across the TCCoA (Thunderbird/Cougar Club of America) site, an excellent resource for these models. Check out this page on MAF cleaning:
http://www.tccoa.com/articles/intake/mafclean.html
http://www.partsgalaxy.com claims list on the genuine Ford MAF for this vehicle is $180.07 (I haven't bothered calling a dealer to verify). Parts Galaxy's price for the genuine article is $147.66
http://www.rockauto.com has 2 reman MAFs:
A1 CARDONE $76.79, core $32; AutoZone's price on this: $89.99, core $35
AC Delco $92.79, core $71.50
Good luck..

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"Ray L. Volts" wrote:

Wow - thanks! I had no idea they were that cheap (I was thinking they were an $800+ part).
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